Signaling system



July 1, 1941. K. I .BURGENER 23475477 SIGNALING SYSTEM Filed March 1,'1949 8' Sinister-Sheet 1 July 1, 1941. m L. auRGENr-:R

SIGNALING SYSTEM Filed arch 1, 1940 muoo EN ENQ Emu Q l o July 1, 1941.K l. auRGi-:NER

SIGNALING SYSTEM Filed Harsh l, 1940 8 Shasta-Sheet 3 www? @mmv mm3 vm@x Sm k wt INVENTOR KARL L. BURGENER M if' ATTORNEYS,

July 1, 1941. K. l. BURGENER SIGNALING SYSTEM Filed March l, 1940 8Sheets-Shale?. 4

INVENTOR KARL L'. BURGENER ATTORN EY5 July 1, 1941. K. L suRGENl-:R

S IGNALING SYSTEM Filed March 1, 1940 8 Sheets-l-Shet 5 @om s mm RS KARLL. BURGENER ATTORNEYS,

Patented Juiy l, 194i i mi SHGNG SYSTEEM application March l, llifit,Serial No. 321,66@

V(lLi. 179-5) 3l Claims.

'lhe present invention relates to signaling systems and, moreparticularly, to improvements in telephone systems for use in policedispatching systems.

A conventional police dispatching system comprises a dispatcher positionat' which calls on telephone lines extending to telephone stationsdisposed in police boxes are answered, and from which calls are extendedover trunk lines to different destinations. In a system of this type thedispatcher at the dispatcher position iirst operates apparatus to answera call and subsequently operates apparatus to extend the call to therequired destination; andin the event a message is to be broadcast inresponse to the call answered, the dispatcher at the dispatcher positioneither extends the call to an announcer position at an associated radiostation or initiates a new call which is extended to the announcerposition. lin any event the actual message is broadcast by the announcerat the announcer position in the radio station.

While a dispatching system ofy the type described is reasonablysatisfactory in service, considerably more time is required in handlingcalls at the dispatcher position than is desirable.

Accordingly, it is an object of the present invention to provide in adispatching system including a dispatcher position, improved circuitapparatus which is so connected and arranged that the handling oi callsat the dispatcher po sition is rendered exceedingly fast.

Jituiotlrer object oi this invention is to provide in a telephone systemincluding an operator position provided with apparatus for answeringcalls on associated telephone lines and apparatus for extending callsover associated trunk lines, a control arrangement responsive to theoperation of the call-answering apparatus for operatlng, at leastpartially, the call-extending apparatos.'

Another object of the invention is to provide in a telephone exchangeincluding an operator position provided with apparatus for answeringcalls on associated telephone lines, improved. switching apparatus forextending the calls which is governed jointly by automatic means andmanual means under the control of the operator at the operator position.

A further object of the invention is to provide in a signaling systemcomprising an operator position and a radio broadcasting stationincluding a radio transmitter, improved switching apparatus controllablefrom the operator position for answering calls on associated telephonelines and for completing direct connections to the radio transmitter.

A further object of the invention is to provide in a telephone systemcomprising a number of operator positions, each including apparatus foranswering calls on associated telephone lines and apparatus forcompleting connections over associated links, improved apparatuscontrollable from each operator'position to identify a. telephone lineincluding in a connection completed over any one of the associatedlinks.

The features of the present invention are illustrated as beingincorporated in a signaling system comprising a dispatcher exchange oi?the combination manual and. automatic type including a number ofdispatcher positions and termihating a plurality of manual telephonelines, a private exchange of the automatic type includingan automaticswitch trainand terminating a plurality of automatic telephone lines,and a radio broadcasting station of conventional type including a radiotransmitter.

In accordance with one feature of the invention the system comprises aplurality of lines, a plurality of links, a plurality of trunksindividually associated with the lines, an operator position, meansselectively controllable from the operator position for connecting theoperator position to any one oi the lines, thereby to answer a call onthe one line, means controlled when the operator position is connectedto one ol' the lines for connecting the one line to an idle one or thelinks, an impulse sender controllable from the operator position, meanscontrolled when the one line is connected to 'the one linlk forconnecting the impulse sender to 'the one of the trunks associated withthe one link, impulse responsive switching apparatus associated with theone trunk, and means for connecting the one link to the one trunk.

In accordance with another feature oi the invention, the operatorposition is disposed in a dispatcher exchange and the automatic switchtrain associated with the trunks is disposed in a private exchange, theoperator position being provided with a plurality of line keysindividually associated with the lines and a plurality of linktrunk keysindividually associated with the links and the trunks. Moreparticularly, each of the line keys is operable to connect the operatorposition to the associated line; and each of the link-trunk keys isoperable to connect the operator position to the associated' link andtrunk. Also an arrangement comprising a link distributor is provided forassigning idle ones of the In accordance with another feature of theinvention the system comprises a plurality of police telephone stations,telephone :lines individually extending between the police telephonestations and a dispatcher exchange, a radio broadcasting stationincluding a radio transmitter, and a trunk extending between thedispatcher exchange and the radio transmitter. Means is provided at eachof the police telephone stations for initiating a call on the associatedtelephone lines; and means is provided in the dispatcher exchange whichis controlled from the dispatcher position for connecting positionequipment provided thereat to the trunk, the position equipmentincluding a telephone instrument. Finally means is provided in thesystem which is controlled when the position equipment is connected tothe trunk for rendering the radio transmitter operative for broadcastpurposes.

In accordance with a further feature of the lnvention, the systemcomprising a plurality of operator positions, a plurality of groups oflinks individually associated with the operator positions, a pluralityof groups of trunks individually associated with the groups of links,whereby the individual trunks in a given group of trunks areindividually associated with the links in the corresponding group oflinks, means selectively controllable from any one of the operatorpositions for connecting the operator position to any one of the lines,means controllable when one of the operator positions is connected toone of the lines for connecting the one line to an idle one of the linksin the associated one of the groups of links, an impulse sendercontrollable from the one operator position, means controlled when theone line is connected to the one link in the one group of links forconnecting the impulse sender to the associated one of the trunks in theone group oi trunks, impulse responsive switching apparatus associatedwith the one trunk in the one group oi trunks, and means for connectingthe one link in the one group of links to the one trunk in the one groupoi trunks.

in accordance with a further feature of the inevention, the systemcomprises a plurality of automatic switches individually associatedwith. the

"lines, means controlled when a cali on one of the lines is answered atone of the operator positions for marking an idle one of the links inthe associated one of the groups of links and for initiating operationof the assiated one of the switches, means controlled when the oneswitch seizes the marked link. for removing the marking from thelast-mentioned link and for arresting operation of the one switch,thereby to complete a connection between the one line and the one liniein the one group of links, means controlled when one of the switches isoperating for preventing operation of the other of the switches, andmeans controlled when a link: in one oi the groups of links is markedfor preventing marking of a link in any other of the groups of links.

ln accordance with a further feature oi the invention, the systemcomprises a plurality of lines, a plurality of operator positions, aplurality of groups of links individually associated with the operatorpositions, means at each operator position for extending a number ofdifferent connections from the lines over the diiferent links'in theassociated group of links, a plurality ot identity apparatusindividually corresponding to the operator positions, each identityapparatus vbeing operative selectively to identify the particular linesincluded in the different connections extended over the links in thegroup of links associated with the corresponding operator position,normally effective means at each operator position for selectivelyoperating the corresponding identity apparatus, and means including anidentity distributor controlled by the operation of one of the identityapparatus for preventing operation of the other of the identityapparatus. More particularly, the identity distributor is connected andarranged to prevent simultaneous operations of two of the identityapparatus in spite of the fact that the two identity'apparatus areseized substantially simultaneously at the two corresponding operatorpositions.

Further features of the invention pertain to the particular arrangementof the circuit elements thereof, whereby the above-outlined andadditional operating features are attained.

The novel features believed to be characteristic of the invention areset forth with particularity in the appended claims. The invention, bothas to its organization and method of operation, together with furtherobjects and advantages thereof, will best be understood by reference tothe following specification taken in connection with the accompanyingdrawings in which Figure 1 illustrates the general arrangement of asignaling system including a central oice, a private branch exchange orP. B, X, a dispatcher exchange, a private automatic exchange or P. A. Xand two radio stations and embodying the present invention; Figs. 2 to8, inclusive, taken together, illustrate the details of a signalingsystem having incorporated therein the features of the invention, asbriefly outlined above; and Fig. 9 illustrates the mode of combiningFigs. 2 to 3, inclusive, oi the drawings to form a unified system.

Description of the apparatus incorporated in the signaling systemReferring new more particulariy to Fig. l of the drawings the signalingsystem there iilustrated comprises a central oice iii, a l?. E. Iii. adispatcher eachange a P. El two radio stations 5@ and The central officeiti may be of any well-known type; the P. E. 2 i223 is of the manualtype; the dispatcher exchange is of the combination manual and automatictype; the P. 2 is of the automatic type; and tbe radio stations and areci conventional type. Tae Ts. X Z@ comprises op ior position at whichgroup of twoK way Eines, including the trunk line extend g betale n tnecentral office t@ and the P. ted.

including the first dispatch second. dispatcher position S rione linehaving a line circuit individu'l associated therewith extends to eachtelepnone station in the dispatcher exchange Sil. telephone line Ztiiextends to the telephone station Ti and has the line circuit Zilliindividually associated therewith. Each of the telephone stations in thedispatcher exchange 3ft is located in a police box and comprises theusual telephone station equipment including a telephone instrument and aringer.

.also a group of two-Way trunk lines entends r1 tele aesmvv change 30has a trunk circuit individually assoelated therewith, the trunk circuitbe@ being 1ndividually associated with the trunk line hib. Further agroup of one-way trunk lines extends from each dispatcher position inthe dispatcher exchange til to the P. A. X til. For example, the v groupoi' trunk lines extending from the rst dispatcher position 600 in thedispatcher exchange 30 to the P. A. X t0 includes the trunk line Tit.`

Each trunk line extending from a dispatcher position in the dispatcherexchange t@ to the P. A. X du terminates in a selector switch in theA P.A. X im, the trunk line 110 terminating in the selector switch 82d inthe P. A. X lid. Also a first group of one-way trunk lines, includingthe trunk line 2id, and a second group of one-way trunk lines, includingthe trunk line tilt, extend between the P. A. X di! and the dispatcherexchange te. Each of the trunk lines in the first group is provided wthan individual line circuit in the dispatcher exchange til. the linecircuit 2lb being individual to the trunk line 210; while each oi' thetrunk lines in the second group is directly connected to a`corresponding one of the telephone lines in the dispatcher exchange 3d,the trunk line Mii being directly connected by way of the cable ttt tothe telephone line 2M extending to the telephone station Ti. Finally thedispatcher exchange 3d and the radio stations it and til areinterconnected by the trunk lines itt and liti, .the trunk line 'ltdextending from each dispatcher `position in the dispatcher ex change il@to the radio station and the trunk line 'ltd extending from eachdispatcher posi tion in the dispatcher exchange 3B to the radio station6d.

The P. A. X du serves a number of subscriber substations, including thesubscriber substation Tt, and comprises an automatic switch trainincluding a number of finder-selector links, a number oi connectorswitches and 4a. number of groups of selector switches respectivelyterminating the groups oi trunk lines extending from the variousdispatcher positions in. the dispatcher exchange t@ to the P. A. X im.More particularly, the switch train comprises the lnder-selector linlrvtte, including the finder switch dit and the selector switch e327, theconnector switch @2i and y the selector switch dit. Finally it is notedthat a telephone line dtd extends to the subscriber substation T2. Thefinder switch dit has access to each telephone line in the P. A. X dii;while theA selector switch d2? has access to each trunk line in thefirst group ci trunk lines extending between the P. A. X it and thedispatcher exchange :iii and to each connector switch in the P. A. X dd.The connector switch cti has access to each telephone line in the P. A.X il@ and to each trunk line in the second group of trunk linesextending between the P. A. X it and the dispatcher exchange dit.Finally the selector switch d2@ has access to each connector switch inthe P. A. X titi. Each subscriber substation in the P. A. X it is numberoilv groups of links individually associated with the various dispatcherpositions, the rst link 30D and the second link dit being included in agroup of links individually associated with the rst dispatcher positiontdt. Also it is noted that the line circuits terminating the telephonelines in Ithe dispatcher exchange til and the line circuits terminatingthe trunk lines in the iirst group of .trunk lines extending from the P.A. X lil to the dispatcher exchange 3d comprise finder switches havingaccess to the links in each group of links. For example, the line cir=cuit 2do comprises a finder switch Sie@ and the line circuit M5comprises a iincierA switch Smid, the nder switches S23@ and Std@ havingaccess to the first link Bilt and the second link ,Slt in the group oflinks individually associated with the first dispatcher position ddii inthe dispatcher exchange iii.

Finally the dispatcher exchange d@ comprises a link distributor im@ andan identity distributor unit btt commonly associated with the variousdispatcher positions, which are utilizedV for purposes more fullyexplained hereinafter. In order to facilitate communication between thedispatcher positions in the dispatcher exchange 39, order trunks areprovided therebetween, the order trunk 6d@ extending between the iirstdispatcher position itil@ and the second dispatcher position ttt. Eachdispatcher position in the dispatcher exchange til has a sender controlcircuit and a sending key set individually associated therewith, thesender control circuit @te and the sending key set Kbit beingindividually associated with the first dispatcher position dtd.

he sender control circuit dit@ comprises a nder switch Sutil havingaccess to each trunk line in the group of trunk lines extending from theiirst dispatcher position ttt in the dispatcher exprovided with theusual substation equipment in- Y cluding a telephone instrument, a dialand a ringer.

Also the dispatcher exchange di? comprises a change Zit to the P. A. Xt@ and a under switch Sti@ having access to a group of digit registers,including the digit register ttt, provided in the dispatcher exchangefit.

The operator position i335 in the P. B. X 2d, shown. in Fig. 8,comprises conventional apparatus including a telephone instrument andequipment for answering and for completing connections between thecentral oilce it, the various telephone lines in the P. B. X 2d and thedispatcher exchange d. Preferably, the switches included in the switchtrain in the l?. A. X shown in Fig. il, and including the finder switchttt, the selector switch the connector switch dit and the selectorswitch `are oi the usual Strowger type. Preferably, the apparatus in thetwo radio stations ti@ and shown in Fig. d, Yare identical, theapparatus respectively comprising the radio broadcast transmitters ddiiand @titi of conventional connection and arrangement.

Preferably, each of the line circuits terminating a telephone line inthe dispatcher exchange 3@ and each of the line circuits terminating atrunk line in the iirst group of trunk lines extending from the P, A. Xit to the dispatcher ex-V the rotary switch S23@ is provided with arotary mag-net M231 for moving the wipers noted in the rotary direction.Further the line circuit Zili comprises a number of relays including aline relay Riti?, a cuto'i relay R205 and a switching links individuallyassociated with the dispatcher positions in the dispatcher exchange 30is identical to the first link 300 in the group of links associated withthe first dispatcher position 600, shown in Fig. 3. The first link 300comprises :a repeater 305 operatively interconnecting a rst branch ofthe rst link 30K! including the trunk 750, and a second branch of thefirst link 300 including the cable 380. Further the first link 30Dcomprises a number of relays including a start relay R3iil, a stop relayR320, a control relay R330, a hold relay R325, a line relay R340, asupervisory relay R350 and a cut-in relay R360 connected and arranged ina manner more fully described subsequently.

The link distributor 400, shown in Fig. 4, com.- prises four cutoirelays R410, R420, R430 and R446 individually associated with the fourdispatcher positions in the dispatcher exchange 30 and four hold relaysR405, R4l5, R425 and R435 individually associated with the fourdispatcher positions in the dispatcher exchange 30. The particularconnection and arrangement of the cutoi and hold relays mentioned aredescribed more fully subsequently.

The identity distributor unit 500, shown in Fig. 5, comprises fourcutoff relays R520, R530, Rist@ and R individually associated with thefour dispatcher positions in the dispatcher exchange 3@ and fouridentity relays Riil and R566, the reference character `Rl indicatingthree of the identity relays, individually associated with the fourdispatcher positions in the dispatcher exchange 3u. The particularconnection and arrangement of the cutoff and identity relays mentionedare described more fully subsequently.

Freierably, the trunk circuit associated with each of the trunk linesextending between the .lf2 @tand the various dispatcher positions in thedispatcher exchange 3@ are identical to the trunk circuit shown in Fig.5, individually associated with the trunk line @i5 extending between theX 5i@ and the first dispatcher position i il in the dispatcher exchangePill. rl'he trunk circuit comprises a ring-up relay totf relay Reli?connected and arranged in e. i er more fully described subsequently.

Fre aly, each of the dispatcher positions in r fcher exchange isidentical, to the rst spatcher position shown in Figs.

repeater f5 it, impedance element ano. e. number or" lys including thecontrol rela-y and two and connected .and

ore fully described sub- .r circuit at the rst dis comprises number o'line keys individually assoc" ted with the telephone lines in thedispatcher' nange the line key being individually associated with thetelephone line lill extending to the telephone station Ti; number oftrunk keys, not shown, indi vidually associated with the trunk lines inthe first group of trunk lines extending from the F. A. l@ to thedispatcher exchange 3d; a number oi link keys individually associatedwith the links in the associated group of links, the link key Kit@ being`individually associated with the rst link til@ in the associated groupof linlm; and a number of link identity keys individually relays Rf G,which comprises trunk. circuit including associated with the links inthe associated group of links, the link identity key K160- beingindividually associated with the rst link 300 in the associated group oflinks. Further the trunk circuit at the first dispatcher position B00comprises a number of P. B. X keys individually associated with thetrunk lines in the group of trunk lines extending between the rstdispatcher position @tu and the P. B. X 20, the P. B. X key Kl I0 beingindividually associated with the trunk line 5l@ included in the group oftrunk lines extending between the first dispatcher position 6120 and theP. B. X 20; a radio station key K12!! commonly associated with the trunklines '|80 and T85 extending between the dispatcher exchange 30 and theradio stations 50 and 80, respectively; and a number of order keysindividually associated with the order trunks extending between' thefirst dispatcher position B00 and the other dispatcher positions, theorder key K640 being individually associated with the order trunk 680extending between-the first dispatcher position 600 and the seconddispatcher position 800. Finally the trunk circuit at the rst dispatcherposition @lill comprises a common ring key X625 which is operative toring over a connection associated with the-'rear end of the trunkcircuit, and a common split key K146i which is operative to split ineither direction a connection associated with the front end of the trunkcircuit.

Also associated with the r'st dispatcher posi-Y tion E06 are variousgroups of signal lamps which are provided in order to facilitate thesupervision of the various connections. For example, the identity signallamp L63?, the lbusy signal lamp Liilt and the line signal lamp L53@ areindividually associated with the cable 250 extending to the line circuit2li@ individually associated with the telephone line EN extending to thetelephone station Tl; the call signal lamp Litt, the answer signal lampL'lil and the busy signal lamp Lll .are individually associated with thecable titi@ extending to the rst link Stu; the signal lamp L'ttisindividually associated with the trunk circuit still which isindividually associated with the trunk line 575 extending between thefirst dispatcher position tu@ in the dispatcher exchange and the P. B. X2t; and the signal lamps and Lit@ are individually associated with therespective trunks iti@ and extending from. the first dispatcher positionthe dispatcher exchange to the radio stations il@ and respectively.

The sending key set K365i, the sender control circuit and the digitregister are connected and arranged in a conventional manner;

in view of the fact that the particular connection and arrangement ofthis apparatus forms no part of the present invention, the detailsthereoi have not been illustrated in the interest of brevity. However,for reference purpose, a sending key set, a sender controi circuit and adigit register or the general character of the sending key set thesender control circuit and the digit register respectively, aredisclosed respectively in Fig. i6, Figs. l5 and i6,

and Figs. l? to 2l, inclusive, of Thomas F. Crocker Patent lilo.Zl'i'jlil, issued August l, 1939.

A better understanding of the connection and arrangement of theapparatus incorporated in the signaling system will be facilitated froma consideration of the detailed operation of the various pieces o.apparatus incorporated therein incident to the completion and thehandling of the various' connections at the first dispatcher asentarposition tot in the dispatcher exchanger to and at the operatorposition. dit in the P. B. X iii,

as will appear hereinafter.

General operation of the signaling system Considering now the generaloperation oi the signaling system with reference to Fig. 1 of thedrawings, it is noted that a call initiated at any one oi.' thetelephone stations in the dispatcher exchange tt, such, for example, asthe telephone station Ti, causes a signal to be transmitted to each ofthe dispatcher positions in the dispatcher exchange tt and may beanswered at any one of the dispatcher positions, such, for example, asthe rst dispatcher position tdt. In order to answer the call from thetelephone station 'I'il on the telephone line itl, the dispatcher at theiirst dispatcher position dii@ operates the line key in his trunkcircuit individually associated with the telephone line Edi thereby tocause the nder switch Siti@ lin the line circuit ddii individuallyassociated with the telephone line Edil to operate and iind an idle oneof the links in the group ci links individually associated with thefirst dispatcher position ttt, such, for example, as the iirst link tdt.Immediately the dispatcher at the nrst dispatcher position tilt operatesthe line lrey in his trunk circuit corresponding to the telephone linetdi extending to the telephone station Ti, a connection is. completedbetween the irst dispatcher position tti? and the telephone station Tl;and immediately the :lnder switch Sit@ in the line circuit tttindividually associated with the telephone line tdi seizes the rst linktot, operation or the sender control circuit ttt/individually associatedwith the iirst dispatcher position ttt is initiated. More particularly,the iinder switch Sttii of the sender control circuit tdt iinds thetrunk dit connected to the iirst link 3d@ and to the trunk line il@extending from the first dispatcher position tilt in `the dispatcherexchange t@ to the P. A. X dii. Also the finder switch Sdi@ of thesender control circuit tot iinds an idle one of the digit registers,such, for example, as the digit register dtd. Accordingly, at this time,the apparatus at the first dispatcher position ttt is automaticallyconditioned to extend the call therefrom by way of the trunk line il@ toany subscriber substation in the P. A. X lit, in the event this serviceis desired.

In the event the call is to be extended from the first dispatcherposition ttt in the dispatcher exchange t@ to a Isubscriber substation,such, for example, as the subscriber substation TZ in the P. A. X dd,the dispatcher in the rst dispatcher position tilt operates the sendingkey set Kdiiii, thereby to cause appropriate digits to be registered inthe digit register dtd, whereupon the digit register tilt governs thesender control circuit tilt in order to cause the digits to betransmitted over the trunk line llt to the P. A. X til. The digitstransmitted over the trunk line il@ to the P. A. X du control theautomatic switch train therein in order to cause the call to be extendedto the subscriber substation T2 in a. Well-known manner, thereby toestablish. a connection between the telephone station Ti in thedispatcher exchange t@ and the subscriber substation T2 in the P. A. Xit The dispatcher at the first dispatcher position Gilt may then operatethe link key in his trunk 'circuit individually associated with thefirst link 3mi and then return the line key in his trunk circuitindividually associated with the telephone iii line tdi to its normalposition, thereby to caus a three-way communication connection to becompleted including the telephone station Ti, the trunk. circuit at therst dispatcher position ttt. and the subscriber substation Ti. Furtherit is noted that, 'when the line key in the trunlr circuit at the nrstdispatcher position tilt in#l dividually associated with the telephoneline iti is operated inA order to answer the call on the telephone linetiti, the lint: distributor ddii opcrates in order to loch out the otherdispatcher positions, thereby to prevent the call on the telephone linetti from being answered at the other dispatcher positions. i,

After the connection has been established ben tween the telephonestation 'lli in the dispatcher exchange t@ and the subscriber substation'It in the P. A. X dit, the dispatcher at the iirst dise patcherposition tot may tree the trunls circuit at his position by returningthe link hey in his trunk circuit individually associated with the firstlink tt@ to its normal position. Further it is noted that the dispatcherin the first dispatcher position dell may monitor or split in eitherdirection the established connection between the telephone station Il inthe dispatcher exchange td and the subscriber substation Ti in the P. A.X di?. Finally it is noted that the release of the establishedconnection between the telephone station 'Ii in the dispatcher exchangetiti and the subscriber substation Ti in the P. A. 2 dit is under thecontrol oi the dispatcher at the nrst dispatcher position ddii; and thatthe dispatcher at the rst dispatcher position tilt may control theidentity distributor unit ddii by operating a link identity key in histrunk circuit individually associated with the firstY link tot, therebyto cause the particular telephone station included in the establishedconnection, routed by way of the first link tilt, to be identified.'I'he identity distributor unit tdt is so connected and arranged that,when it is taken for use by the dispatcher at the first dispatcherposition tilt to identify a telephone station, it is locked against usebythe dispatchers at the other dispatcher positions.

Further it is noted that a call may be extended from any one of thedispatcher positions in the dispatcher exchange til to anyone of thetelephone stations in the dispatcher exchange 33t or to the operatorposition 835i in the l?. B. X 2d and from the operator position dit inthe P. B. X 2d to any one of the dispatcher positions in the dispatcherexchange dd, in a manner more fully explained hereinafter. Further,calls may be set up in either direction between the central ofiice i@and the P. B. X 2d and then routed to any one of the dispatcherpositions in the dispatcher exchange 3d. vThe dispatcher at any one ofthe dispatcher positions in the dispatcher exchange t@ may route a callfrom his position to either one of the radio stations 5t or tl), therebyto 'broadcast directly irom the dispatcher position therein, in a mannermore fully explainedhereinafter.

Initiation of a coll ci o telephone station in the dispatcher exchange Acall may be initiated at a telephone station in the dispatcher exchanget0, such, for example, as the telephone station Tl, by removing thereceiver of the telephone instrument thereat from its associatedswitchhooi. When the receiver oi the telephone instrument at thetelephone station Ti is removed from its associated switchhoolr, abridge path is completed thereat between the line conductors C262 andC203 of the telephone line 20| extending to the telephone station Tl.'When this bridge path is completed between the line conductors of thetelephone line till a circuit is completed for energizing the winding orthe line relay R2i6. This circuit extends from ground by way oi thecontacts 206, C262, the bridge path between the line conductors C262 andCd of the telephone line 2M at the telephone station Ti, C203, thecontacts 207| and the winding of B2i@ to battery. When thus energizedthe line relay Rill@ operates to complete, at the contacts 2li, anobvious path for applying ground potential to the control conductor C266of the telephone line 20|. IThis application of ground potential to thecontrol conductor C300 o the telephone line Edi completes a pathextending by way oi the control conductor C26? in the cable 266" forapplying ground potential to the control conductor of the trunk line 610exten from the P. A. X l0 to the dispatcher exchange 60 in order to markthe trunk line liti and consequently the telephone line 20| as busy tothe connector switches in the P. A. X 60. Further the line relay B2i@completes, at the contacts tit, an obvious path for applying groundpotential to the control conductor C266 in the cable 260, thereby tocomplete an obvious circuit for illuminating the line signal lamp H566at the iirst dispatcher position 600 and the corresponding line signallamps at the other dispatcher positions.

The illumination of the line signal lamps at the various dispatcherpositions indicates to the dispatchers thereat that a call is waiting tobef answered on the telephone line 20| extemslingl to the telephonestation TI. In order to answer the call on the telephone line 20| thedispatcher at one of the dispatcher positions operates the line key inhis trunk circuit individually corresponding to the telephone line 20|.Assuming that the call on the telephone line 20| is answered at the rstdispatcher position 600, the dispatcher thereat operates the line keyK630i in the trunk circuit at the rst dispatcher position 600 away fromits normal position, thereby to complete, at the contacts 633 and 636thereof, obvious connections between the line conductors C610 and C61!of the trunk circuit at the rst dispatcher position 600 and therespective line conductors C202 and C206 of the telephone line 20|. Alsowhen the line key X630 is thus operated there is completed, at thecontacts 635 thereof, an obvious path for applying ground potential tothe control conductor C612, thereby to complete an obvious circuit forenergizing the upper winding of the control relay R655. When thusenergized, the control relay R656 operates to complete, at the contacts651, an obvious circuit, including the grounded control conductor C612,for energizing the winding of the switching relay R660. When thusenergized, the switching relay R660 operates shortly thereafter, thisrelay being of the slow-to-operate type, to complete,

at the contacts 666, an obvious holding circuit including the groundedcontrol conductor C612 for energizing the winding thereof. Further theswitching relay R660 interrupts, at the contacts 665, the previouslymentioned circuit for energizing the upper winding of the control relayR655, thereby to cause the control relay R655 to restore shortlythereafter, the latter relay being of the slow-to-release type.

Also, upon operating, the switching relay R660 completes, at thecontacts 66d and 663, a connection between the repeater 6116 and theline conductors C202 and C206 of the telephone line ,i 20|, thisconnection extending from the line conductor C202 of the telephone line20| by way of the contacts 666 of the line key X630, C616, the contacts627 of the ring key H625, C613, the contacts 66|, the condenser 6M, thewindings tii and 6i2 of the repeater 6i0, the contacts 666, C616, thecontacts 6% oi the ring key X626, C670 and the contacts 666 oi the linekey X660 to the line conductor C203 oi the telephone line 20B.Accordingly, at this time, the telephone instrument at the telephonestation Ti is operatvely connected by way of Vthe previously tracedcircuit to the repeater 6|0 at the iirst dispatcher position 600.Further the switching relay R660 completes, at the contacts 662, acircuit for supplying operating current to the transmitter 60|, assumingthat the plugs P606 and P665 occupy their inserted positions into thejacks .1606 and J 606, respectively, at this time. This circuit extendsfrom ground by way of the winding 613 of the repeater 6|0, the jack.1606, the plug P603, the transmitter 60|, the plug P605, the jack J606, the contacts 662 and the retarder coil 601 to battery. Further itis noted that a signal current path is completed which extends fromground by way of the winding 6|3 of the repeater 6|0, the jack J606, theplug P603, the transmitter 60|, the plug P605, the Jack J606 and thecondenser 606 to ground. The above-traced signal current path by-passesthe previously traced cir'- cuit for supplying current to thetransmitter 60 I. Also the receiver 602 is operatively associated withthe winding 6| 2 of the repeater 6i0 by way of a circuit extending fromone terminal of the receiver 602 over the plug P603, the Jack J60l, thecondenser 6|5, the winding 6I2 of the repeater 6l0, the jack J606 andthe plug P605 to the other terminal of the receiver 602. Accordingly, atthis time. the transmitter 60| and the receiver 602 are operativelyconnected to the repeater 6I0. Hence, a two-way communication connectionis completed at this time between the telephone station Ti and the iirstdispatcher position 600.

At this point it is noted that, upon operating, the control relay R656completes, at the contacts 656, a path for short-circuiting the receiver602, which path is interrupted at the contacts-656 incident to therestoration of the control relay R655. 'I'his path is completed andsubsequently interrupted in order to prevent disagreeable clicks frombeing produced in the receiver 602 incident to the operation of theswitching relay R660. The path for short-circuiting the receiver 602extends, when completed, from one terminal of the receiver 602 by way ofthe plug P603, the jack J606, the contacts 656, the jack J606 and theplug P605 to the other terminal of the receiver 602. Further it is notedthat the impedance element I6|6 is connected across the line conductorsC613 and C616 of the trunk circuit at the first dispatcher position 600,this connection extending from ground by way oi the upper winding or mitto the line conductor Ctlt and'irom battery by way oi the lower windingof Itlt to the line conductor Ctllfi. Accordingly, battery is suppliedby way of the impedance element Itid to the telephone instrument at thetelephone station Tl at this e.

Also 'when the line key Kilt@ is thus operated there is completed, atthe contacts titl thereoi, an obvious path for applying ground potentialto the control conductor Citi in the cable itil, thereby to complete anobvious circuit for energizing the winding of the cutoil relay Rllll.When thus energized the cutod relay Ritt operates Ato com plete, at thecontacts tilt, an obvious path ior applying ground potential to thecontrol conductor Citt in the cable litt, thereby to coinplete anobvious circuit for illuminating the busy signal lamp lidad at themst-dispatcher position ttt and the corresponding busy signal lamps atthe other dispatcher positions. The illumination of the busy signallamps at the various dispatcher positions indicates to the dispatchersthereat that the telephone line Ztl is now busy. Further the cutod relayRitt interrupts, at the contacts ttt, a circuit traced hereinafter forenergizing the rotary magnet Miti of the iinder switch Sit@ andinterrupts, at the contacts ttt and till, the previously traced oircuitfor energizing the winding of the line relay Rl lil, thereby to causethe latter relay to restore shortly thereafter, the latter relay beingof the slow-to-release type, and to clearl the telephone line tbl ofimpedance elements. Upon restoring, the line relay Rt it interrupts, atthe contacts it Il il, the previously mentioned circuit for illuminatingthe line signal lamp Litt at the iirst dispatcher position ttt and thecorresponding line signal lamps at the other dispatcher positions,thereby to indicate to the dispatchers at the various dispatcherpositions that the call on the telephone C26! and Ctiil in the cablettt, thereby to retain i the application of ground potential upon thecontrol conductor of the trunk line bill extending from the P. A. X tuto the dispatcher exchange it.

Further when the line key Kbit is operated there is completed, at thecontacts @it thereof, a circuit for energizing in series the winding ofthe cutoff relay Riti@ in the link distributor ftllil and the winding ofthe start relay included in one oi the links in the group of linksindividually associated with the first dispatcher position tilt, theparticular one of the start relays, the winding of which is energized,depending upon the condition of the chain circuit included in the groupoi links mentioned for energizing the windings of these start relays.lin the present example, assuming that the first link ttt in the groupof links individually associated with the first dispatcher position butis idle, a circuit `is completed for energizing in series the winding ofthe cuto relay Rill@ in the link distributor tu@ and the winding of thestart relay Rlu in the iirst link tilt. This circuit extends from groundv by way of the contacts its, ist and tra, the

winding of Ritiii, the contacts titl, the control conductor in the cablett, the contacts 632 of the line key Kbit, the control conductor C255 inthe cable ttt, the contacts Slt and ttt and the winding of Ril@ tobattery. When thus energized the start relay RMU operates to prepare, atthe contacts 3l l, a circuit traced hereinafter for energizing thewinding of the stop relay Bildt, to complete, at the contacts tit, anobvious holding circuit for energizing .the winding thereof by way ofthe grounded control conductor Gibt in the cable ttt and to interrupt,at the contacts Zitti, a point in the previously traced circuit forenergizing the winding thereof. Further ,the start relay Rill@ prepares,at the contacts dit, a circuit traced hereinafter for energizing thewinding of the hold relay Rtillb in the link distributor ttt. Finally,the start relay Rill@ completes, at the contacts tilt, a circuit forenergizing the rotary magnet Miti of the nder switch Slut, this circuitextending from ground by way oi the contacts 335, tt and tit, thecontrol conductor Citi in the cable itil, the contacts ttt oi the linekey Klitt, the control conductor Citt in the cable ttt, the contactstilt and tdt and the rotary magnet M2371 to battery. When' thusenergized the rotary magnet M2M operates to interrupt, at the contacts23d, the previously traced circuit :for energizing the .rotary magnettutti and to condition the wipers noted of the finder switch Sutil to bedriven one step in the clockwise direction. The rotary magnet Milli!then restores in order to drive the wipers noted of the nder switchStill one step in the clockwise direction and to recoxnplete, at thecontacts itil, the previously traced circuit for energizing the rotarymagnet M2M. Accordingly, the `rotary magnet Mltl'l operatesintermittently, thereby to drive the wipers noted ofthe lnder switchSiittl lstep by step in the clockwise direction until the vtrunk ttextending to the ilrst link litt is seized,

in a manner more fully described hereinafter.

When the previously traced series circuit for energizing the winding ofthe start relay RM@ in the first link tti! and the outoii relay Riti@ inthe link distributor tu@ is completed, the cuto relay Rtlt alsooperates. Upon operating, the cutoil relay Rill@ interrupts, at thecontacts til, an obvious path for applying ground potential by way ofthe contacts dill and the winding of the cutoH relay Rill@ to thecontrol conductor @tti in the cable tu@ and interrupts, at the contactslit, obvious paths for applying ground potential by way of the contactsdit and the windings o the cutoff relays Riltil and Raitt, respectively,to the control conductors Ctb'l and Ctbd in the cable dell. The controlconductors CM2, Citt?! and Cti'it in the cable tt respectively extend tothe second, third and fourth dispatcher positions. Accordingly, theoperated cutod relay Rulli individually corresponding to the firstdispatcher position dll prevents operation of the cuto relays Ratt, Rttband Ritt@ individually corresponding to the second, third and fourth tortml individually corresponding to the rstdispatcher position tiltremains in its operated position, it is impossible for the dispatchersat the other dispatcher positions to answer incoming calls to thedispatcher exchange ttl. This arrangement prevents interference betweenthe dispatchers' at the various dispatcher positions and causes a callon a telephone line to be answered at the particular dispatcher positionat which the line key individually associated with the telephone line isiirst operated.

Continuing now with the operation of the i'lnder switch S230, when thender switch S2130 seizes the trunk 250 extending to the iirst link 300the previously mentioned circuit for energizing the winding of the stoprelay R320 in the first link 300 is completed, this circuit extendingfrom ground by way of the wiper 23d and engaged contact in theassociated contact bank 2160 of the iinder switch S230, the controlconductor C@ of the trunk 250, the contacts 3H and the winding or' R320to battery. When thus energized the stop relay R320 operates tointerrupt, at the contacts 332, the previously traced circuit forenergizing the rotary magnet M2M, thereby positively to arrest furtheroperation ci the rotary magnet M201 at this time. Further the stop relayR320 completes, at the contacts 323, an obvious circuit for energizingthe windingoi the control relay R330, thereby to cause the control relayR330 to operate shortly thereafter, the latter relay being of theslow-to-operate type. Upon operating, the control relay R330 completes,at the contacts 330, the previously mentioned circuit for energizing thewinding oi the hold relay R005 in the link distributor tilt, thiscircuit extending from ground by way of the contacts 330 and 3h0, thecontrol conductor C-il in the cable 300 and the winding of Ri tobattary. vWhen thus energized the hold relay Raitt? operates tocomplete, at the contacts dit, an alternative holding circuitsubstantially identical to that previously traced for energizing thewinding of the start relay R3l0 and to interrupt, at the contacts 401,the previously traced circuit for energizing the winding of the cutoirelay R690. The cutoff relay R4|0 then restores, therebyto prepare, atthe contacts lll and M2, the previously traced paths for applying groundpotential to the control conductors C052, C031 and C456 in the cable450. The application of ground potential to the control conductors C452,C451 and C458 renders the apparatus at the respective second, third andfourth dispatcher positions again operative to answer incoming calls tothe dispatcher exchange 30. Accordingly, it will be understood that thecutoff relay RMU remains in its operated position in order to disablethe apparatus at the second, third and fourth dispatcher positions onlyduring the brief time interval while the nder switch S230 is hunting forthe trunk 250 extending to the rst link 300.

Also. upon operating, the control relay R330 completes, at the contacts33|, a circuit for energizing the winding of the switching relay R220 inthe line circuit 200, this circuit extending from ground by way of thecontacts 33|, the control conductor C252 of the trunk 250, the wiper 232and engaged contact in the associated contact bank 242 of the iinderswitch S230 and the winding of R220 to battery. When thus energized theswitching relay R220 operates shortly thereafter, this relay being` ofthe slow-to-operate type, to interrupt, at the contacts 220, a furtherpoint in the previously traced circuit for energizing the rotary magnetM231, to complete, at the contacts 223, an obvious holding circuit forenergizing the winding of the cutoff relay R205, and to complete, at thecontacts 22| and 222, a connection between the telephone line 20| andtherepeater 303. The connection between the telephone line 20| and therepeater 305 extends from ground by way of the upper winding of the linerelay R340, the winding 306 of the repeater 305, the line conassai??ductor CESE of the trunk 250, the wiper @0l and engaged contact in theassociated contact bank tali oi the finder switch S230 and the contactstti to the line conductor C202 of the telephone line till; and frombattery by way of the lower winding of the line relay R300, the winding3d? of the repeater 300, the line conductorv Ctt of the trunk 250, thewiper 233 and engaged contact in the associated contact bank 260 of thefinder switch S230 and the contacts 222 to the line conductor @Zta ofthe telephone line zal. When this connection between the telephone line20 and the repeater 303 is completed the upper and lower windings of theline relay Rel are energized, thereby to cause the latter relay tooperate.

Also, upon operating. the control -relay interrupts, at the contacts330, a further point in the previously traced original circuit forenergizing the winding of the start relay Raid and prepares, at thecontacts 333, a point in a circuit traced hereinafter for energizing thewinding of the start relay, not shown, included in the second link 315.Further the control relay R330 completes, at the contacts 332, anobvious path for applying ground potential to the control conductor C301in the cable 330, thereby to complete an obvious circuit forilluminating the busy signal lamp Lil@ at the rst dispatcher position50d. The illumination of the busy signal lamp Lille indicates to thedispatcher at the rst dispatcher position 000 that the nder switch S230in the line circuit 200 has seized the first link 300 in the group oflinks individually associated with the rst dispatcher position 600 and,in the event the call on the telephone line 20| is to be extended to theP. A. X 40, that the rst link 300 will be utilized. Finally, the controlrelay R330 interrupts, at the contacts 335, an obvious path for applyingground potential to the control conductor C308 in the cable 380. Whenground potential is removed from the control conductor C38Bin the cable380, operation of the sender control circuit 806 is'initiated. Moreparticularly, the nder switch S8|0 of the sender control circuit Boperates automatically to nd a trunk extending to an idle one of thedigit registers, such, for example, as the trunk 801 extending to thedigit register 308. When the nder switch S8l0 seizes the trunk 801extending to the digit register 808, further operation of the nderswitch S3l0 is arrested and the digit register 808 is conditioned toregister digits transmitted thereto. Also the finder switch S800 of thesender control circuit 806 is operated to search for the trunk 340marked as a calling trunk by the absence of ground potential upon thecontrol conductor C380 thereof. When the nder switch S809 seizes thetrunk 0|0, further operation thereof is arrested and the sender controlcircuit 806 is conditioned to be operative further in accordance withthe operation of the sending key set K305i in the event the call is tobe extended from the first dispatcher position 600 to the P. A. X 40. Atthis time, a bridge path is completed in the sender control circuit 806by way of the finder switch S30Q between the line conductors C0|| andCBIZ of the trunk 3&0 and, consequently, between the line conductorsC11| and C112 of the trunk line H0 extending from the rst dispatcherposition 5230 in the dispatcher exchange. 30 tojthe P. A. X t0. Whenthis bridge path is completed between the line conductors ofthe trunkline 11.0 the selectorvswitch 820 in the P. A. X 40 is conditioned to beoperative in response to impulses transminted thereto. also atA thistime. the une conductors 011i and C112 of the trunk line 113 arerespectively connected by way of the contacts H33 and 156 of the linkkey X153 to the line conduc tors C335 and 033i in the cable 333extending to the iirst link 303, the link key R150 in the trunk circuitat the iirst dispatcher position 330 being individual to the first link303. However, it is noted that the line conductors`C33i and C333 in thecable 383 are not operatively connected to the repeater 303 in the iirstlink 303 at this time, due to the restored position of the cut-in relayR330.

Upon operating, the line relay R333 completes, at the contacts 331|, anobvious circuit for energizing the Winding of the hold relay R325,thereby to cause the latter relay to operate. Also the line relay R340interrupts, at the contacts 333, a point in a path traced hereinafterfor applying ground potential to the control conductor C333 in the cable330, for a purpose morefully explained subsequently. Upon operating, thehold relay R323 prepares, at the contacts 323, a further point in thepreviously mentioned path for applying ground potential to the controlconductor C333 in the cable 333 and completes, at the contacts 321, anobvious holding circuit for energizing the winding of the control relayR330.

At this time, the call from the telephone station Ti on the telephoneline 23E has been answered by the dispatcher at the rst dispatcherposition 333 and the apparatus in the trunk circuit at the rstdispatcher position 333 is conditioned to extend the call on thetelephone line 33t by way of the iirst link 330, the cable 333 and thetrunk line 333 to the P. A. X 33 in the event this service is desired bythe person at the telephone station Tl. Also, at this time, thetelephone instrument at the telephone station Tl is operativelyconnected by way of the telephone line 33i and the cable 233 to thetransmitter 33t and the receiver 302 at the rst dispatcher position 333.Accordingly, theperson at the telephone station Tl and the dispatcher atthe first dispatcher position 333 communicate with each other and thedispatcher at the iirst dispatcher position 4330 is advised concerningthe extension of the call in the event this service is desired.

i'tensz'on of a call from the dispatcher exchange to the'P. A. X

in the event a call from a telephone station to a dispatcher position,such, for example, as the call from the telephone station Ti to theiirst dispatcher position 333 routed by way of the telephone line 233,the cable 233 and the rst link 333 is to vbe extended to a subscribersubstation in the P. A. X |33, such, for example, as the `subscribersubstation T3, the dispatcher at the first dispatcher position 333initiates the extension of the call by operating the sending key setR333 in accordance with the appropriate series of digits. When thesending key set K303 mitted over the trunk line 110 and operates toselect an idle connector switch in a corresponding group of connectorswitches, such, for example, as the connector switch 33E. The connectorswitch 32| then responds to the following two digits to seize thetelephone line 333 extending to the subscriber substation `'llz in theusual manner. The subsequent operationof the connector switch 32!depends upon the idle or busy condition of the subscriber substation T2in accordance with conventional practice.

After the sender control circuit 306 has transmitted the last digitregistered, it operates to cause ground potential to be applied by wayof the finder switch S333 to the control conductor C332 oi the trunk303. The application of ground potential to the control conductor C332Iof the trunk 3i@ completes an obvious path, in-

cluding the control conductor C332 in the cable 333, for energizing thewinding of the cut-in relay R363, thereby to cause the cut-inrelay R333to operate shortly thereafter, the latter relay being of .theslow-to-operate type. The sending key set 303, the sender controlcircuit 333 and the digit register 303 are then automatically released.Upon operating, the cut-in relay R333 completes, at the contacts 33l, aholding circuit :for energizing the winding thereof, this circuitextending from ground by way of the resistor 33t, the contacts 15|! ofthe link key K133 in the trunk circuit at the iirst dispatcher position303, the control conductor C333 in the cable 333, the contacts 33E andthe winding of R333 to battery. Also the cut-in relay R333 completes, atthe contacts 333, a loop circuit between the upper winding of thesupervisory relay R333 and the repeater 335 in the nrst link circuit 303in the dispatcher exchange 33 and the connector switch 3M in the P. A. X33, 'this circuit extending from the line conductor C'ill of the trunkline 113 byi way of the contacts 333 of the link key K133, the lineconductor C333 in the cable 333, the contacts 333, the winding 333 ofthe repeater 305, the upper winding of R333, the resistor 302, thewinding 333 ofy the repeater 303, the line conductorC33l in the cable333 and the contacts 'E53 of the link key K333i to the line conductorC332 of the trunk line 333, the line conductors Cili and C312 beingconnected together in the connector switch 321i by way of the selectorswitch 330 in the P. A. X 33. When the upper winding of the supervisoryrelay R333 is thus energized this relay does not operate as is thusoperated the digit register 333 previously selected by the finder switchS3i3 of the sender control circuit 303 is governed by way of the sendercontrol circuit 303 to register the digits set up by the dispatcher atthe iirst dispatcher position 333 on the sending key set K305. The digitregister 333 then controls the sender control circuit 333, thereby tocause the digits registered in the digit register 303 to be transmittedby the sender control circuit 303 over the nder switch S339, the trunkBi0 and the trunk line to the P. A. X 30. The selector switch 323 in theP. A. X 40 responds to the first digit trans-e it is of the differentialtype, an obvious circuit being completed at this time for energizing theiower winding thereof, at the contacts 333, incident to the operation ofthe cut-in relay R333.

Further the cut-in relay 'R333 prepares, at the contacts 333, analternative path traced hereinafter for applying ground potential to thecontrol conductor C333 in the cable 333, completes, at the contacts 333,an obvious alternative holding circuit for energizing the Winding of thecontrol relay R333, andI completes, at the contacts 333, an obvious pathfor applying ground potential to the control conductor C333 in the cable333 and consequently to the control conductor C333 of the trunk BH3. Theapplication of ground potential to the control conductor C333 marks thetrunk 3i3 as busy to the iinder switch S803 of the sender controlcircuit 333, thereby to prevent seizure of the trunk 3l3 by the finderswitch S803 when operation of the sender control circuit 333 is againinitiated incident to the extension of another call to the P. A. X 30.

Finally, the cut-in relay R360 completes, at the contacts 362, ankobvious path for applying ground potential .to the control conductorC304 in the cable 380, thereby to com .plete an obvious circuit forilluminating the call signal lamp L'l3A at therst dispatcher position600. The illumination of the call signal lamp L'I13 indicates to thedispatcher at the iirst dispatcher position 600 that the sender controlcircuit 806 has completed its operation and that the connection has beenextended from the first link 300 to the P. A. X 40.

At this time, the dispatcher at the iirst dispatcher position 600 mayreturn the line key K630 in the trunk circuit at his position to itsnormal position in order tomfree the trunk circuit at the rst dispatcherposition 600; on the other hand, the dispatcher at the rst dispatcherposition 600 may retain the line key K630A in its operated positionuntil after the subscriber at the called subscriber substation T2 hasanswered the call extending thereto or -the call has been abandoned, ashe desires. As previously noted, the connector switch 82| operates inaccordance with conventional practice upon seizing the telephone line830 extending to the subscriber substation T2 in the P. A. X 40. Moreparticularly, in the event the subscriber substation T2 is busy at thistime, busy tone current is returned over the previously traced loopcircuit extending between the connector switch 82| in the P. A. X 40 andthe repeater 305 in the rst link 300 in the dispatcher exchange 30. Onthe other. hand, in the event the subscriber substation T2 is idle atthis time, ringing current is projected from the connector switch 82!over the telephone line 830 to the subscriber substation T2 in order tooperate the ringer thereat; and ring-hack tone current is conducted overthe previously traced loop circuit extending between the connectorswitch 2i in the P. A. X t0 and the repeater 305 'in the iirst link 30@in the dispatcher exchange Sil. Tone current conducted over thepreviously traced loop circuit is by-passed around the upper winding ofthe supervisory relay R355) by way of the condenser 3M and energizes thewindings 30u and tilt of the repeater 3535, thereby to cause a similartone current to be induced in the windings tu@ and illl of the repeater33:3 which is 'oy-passed around the windings of the line relay Rfit bythe condenser tilt. The tone current induced in the windings Silo andtilt of the repeater 3585 is returned over the previously traced loopcircuit extending hetween the repeater and the telephone station Ti, andto the trunk circuit at the First dispatcher position tt@ by way ci thetelephone line Eii and the cable it@ in the event the Eine key KS3@occupies its operated position,

lWhen the subscriber at the subscriber substation T2 answers lthe caliby removing the receiver of the telephone instrument thereat from itsassociated switchhook, the connector switch 821i in the P. A. X t@switches through, thereby to cause the current traversing the previouslytraced loop circuit extending between the connector switch mi in the P.A. X t@ and the repeater @t5 of the first link 3Go in the dispatcherexchange 3@ to be reversed, whereupon the upper winding of thesupervisory relay R35@ is energized in the reverse direction. When theupper winding of the supervisory relay R35@ is thus energized this relayoperates as it is of the diierential type. Upon operating, thesupervisory relay R350 interrupts, at the contacts 35i, the previouslymentioned path for applying ground potential to the control conductorC384 in the cable 380, thereby to interrupt the previously mentionedcircuit for illuminating the call signal lamp L1'I3 at the rstdispatcher position 600. When the call signal lamp L113 is extinguishedit indicates to the dispatcher at the first dispatcher position 600 thatthe call from the telephone station Tl in the dispatcher exchange 30 tothe subscriber substation T2 in the P. A. X 40 has been answered.

At this time, the dispatcher at the rst dispatcher position 600 returnsthe line key K630 in the trunk circuit at his position to its normalposition in the event this has not previously been done. When the linekey K630 is returned to its normal position the previously tracedconnection between the line conductors of the telephone line 20| and thetrunk circuit at the rst dispatcher position 600 is interrupted at thecontacts 633 and 636 thereof. Also, at the contacts 635 of the line keyK630, the previously mentioned holding circuit for energizing thewinding of the switching relay R660 is interrupted, thereby to cause thelatter relay to restore. Upon restoring, the switching relay R660interrupts, at the contacts 66| and 663, further points in thepreviously traced connection including the trunk circuit at the rstdispatcher position 600 and interrupts, at the contacts 662, thepreviously traced circuit for supplying current to the transmitter 604.Further, when the line key X630 is returned to its normal position thereis interrupted, at the contacts 636i thereof, a further point in thepreviously traced circuit for energizing the rotary magnet M231 of thefinder switch S230 and, at the contacts 63! thereof, there isinterrupted the previously traced original circuit for energizing thewinding of the cut-oi relay R205. Finally, at the contacts 32 of theline key X630, there is interrupted the previously traced holdingcircuit for energizing the winding of the start relay Rl, thereby tocause the latter relay to restore. Upon restoring, the start relay RME!interrupts, at the contacts 39 l, the previously traced circuit forenergizing the winding of the stop relay R320, thereby to cause thelatter relay to restore. Further the start relay RSG@ interrupts, at thecontacts 362, a further point in the previously traced holding circuitfor energizing the winding thereof, interrupts, at the contacts tilt, aiurther point in the previously traced path for applyinfr groundpotential to the control conductor Citi in the cable 25B, andinterrupts, at the contacts tit, the previously traced circuit forenergizing the winding of the hold relay in the ,L Fink distributorthereby to cause the latter relay to restore.

Finally, upon restoring, the start relay REIG prepares, at the contactsgt3, the previously traced chain circuit between the rst link 360 andthe second link @it for energizing the winding of the start relay, notshown, in the second iink tl'ii. rThis prepared circuit extends from thecontrol conductor in the cable 26@ by way ci' the contacts tit and tolthe control condoctor 03:23 extending to the second link 3'15, batteryby way of the winding of the-start relay in the second link SM5-beingconnected to the control conductor Upon restoring, the

hold relay Rliil prepares, at the contacts ttl', the previously tracedpath for applying ground potential by way or" the contacts tti and thewinding of the cutoi relay Rlii to the control conductor C653 in thecable 56. Accordingly, at this time, it will be understood that the linkdistributor it is completely released and the order to answer a call onthe corresponding telephone line, a circuit substantially identical tothat previously traced is completed for energizing in series thewindings of the cutoff relay RMI) in the link distributor Mill and thewinding of the start relay, not shown, in the second .link 315, thiscircuit extending from ground by Way of the contacts Ml, 133i and 421thewinding of R410, the contactsadm, the controlconductor C453 in the cable45t, the contacts of the link key mentioned in the trunk circuit at thefirst dispatcher position Wil, the control conductor in the'corresponding cable, the control conductor C301, the contacts @it and333 to the control conductor Chit extending to the second link 31d,battery potential by way of the winding of the start relay, not shown,in the second link 315 being applied to the control conductor CMS.Accordingly, at this time, the .trunk circuit at the first dispatcherposition til@ is completely released and the apparatus thereat is inreadiness to answer another call on a telephone` line in the dispatcherexchange 3d.

Supervision and release of un established connection between n telephonestation in the dispatcher exchange and a subscriber substation in the P.d. X

An established connection between a telephone station in the dispatcherexchange 3@ and a subscribed substation in the P. A. X d@ is supervisedby the dispatcher at the particular dispatcher position in thedispatcher exchange at which the connection is set up. For example, theestablished connection between the calling telephone station Ti in thedispatcher exchange t@ and the called subscriber substation T2 in the P.A. X iii and routed therebetween by way of the telephone line iti, theiirst link 5mt, the trunk line 11ll, the selector switch dit, theconnector switch 321 and the telephone line dit@ is supervised by thedispatcher at the hrst dispatcher position tilt. More particularly, theperson at the calling telephone station Tl in the dispatcher exchange 3@has swltchhook supervision and may signal the dispatcher at the rstdispatcher po-f sition Edil by repeatedly operating the .switchhook atthe telephone station Ti, thereby intermittently to interrupt thepreviously traced loop circuit extending between the telephone stationTl and the line relay Riiiill. The line relay RM@ operates and restoresintermittently, thereby intermittently to complete, at the contacts ttt,the

previously mentioned circuit for illuminating the answer signal lampL11d. This circuit extends from. ground by way oiY the contacts @liliand from ground by way of the contacts 32d over the contacts ttt, thecontrol conductor C386 in the cable 38d and the answer signal lamp1.1115 to battery. The intermittent operation of the line relay Rill@causes the answer signal lamp L11@ to lash,lthereby to indicate to thedispatcher at the first dispatcher position Et@ that a person at acalling telephone station in the dispatcher exchange Sil desires thedispatchers service. y

Similarly, the subscriber at the called subscriber substation T2 in theP. A. X t0 has' switchhook supervision and may signal the dispatcher atthe first dispatcher position B00 by repeatedly operating the switchhookat the subscriber substation T2, thereby to cause the connector switch82|! to operate intermittently in order intermittently to cause currentto be reversed overthe previously traced loop circuit extending betweenthe connector switch t2l in the P. A. X il@ and the repeater 305 in therst llink 300 in the dispatcher exchange tu. The intermittent reversalof current over the previously traced loop circuit causes thesupervisory relay R350 to operate and restore intermittently, thereby tocomplete intermittently, at the contacts dhthe previously traced circuitforilluminating the call signal lamp L11t, whereupon the call signallamp L11ii is dashed. The ash ing of the call signal lamp 1.113indicates to the dispatcher at the ilrst dispatcher position ttt that asubscriber at a subscriber substation in the P. A. X til desires thedispatcher's service.

Furthermore, the ilashing of ,the call signal lamp 1.113 or the iiashingof the answer signal lamp L11tl indicates to the dispatcher at the firstdispatcher position litt that the established connection upon which hisservice is desired is routed by way of the ilrst link ttt, the signallamps Llllt and L111 being individual to the iirst link @dit Thedispatcher at `the ilrst dispatcher position ttt then operates the linkkey H15@ to its talk position, thereby to complete, at the contacts 158thereof, an obvious path for applying ground potential to the controlconductor Cats, thereby to complete an obvious circuit for energizingthe lower winding of the control relay R655. When thus energized, thecontrol relay R655 operates to complete, at the contacts 558, an obviouscircuit for energizing the winding of the switching relay Rt, thereby tocause the switching relay R65@ to operate shortly thereafter, the latterrelay being of the slow-tooperate type. Upon operating, the switchingrelay R650 completes, at thel contacts 653, an obvious holding circuitfor energizing the winding thereof including the grounded controlconductor C633 and interrupts, at the contacts litt, the previouslymentioned circuit for energizing the lower winding of the control relayRatti, thereby to cause the control relay R655 to restore shortlythereafter, the latter relay being of the slowtorelease type. Also, uponoperating, the switching relay R650 completes, at the contacts anobvious connection between the windings t i i and @i2 of the repeatertitl and the line conductors C615 and @dit of the trunk circuit at4 thefirst dispatcher position ttt, and completes, at the contacts dit, anobvious alternative circuit for supplying current to the transmittertill.

Also when the link key Kitt is operated to its talk position thepreviously traced direct connection between the line conductors C111 andC112 of the trunk line 11@ and the line conductors C385 and Cf'ltl,respectively, in the cable Zitti are interrupted at the contacts 153 and156, respectively, thereof. Further, at the contacts 15d and 151 of thelink key Kit, there is completed a connection between the lineconductors 011i and C112 of the trunk line 110 and the repeater di@ inthe trunk circuit at the rst dispatcher position ii, this connectionextending from the line conductor C11l of the trunk line 11b by way ofthe contacts 15d of the link key K15I, the line conductor (21M, thecontacts 1d? of the split key K1N, the line conductor C615, the contactttl, the windings lill and tit of the repeater tlt, the line conductorC616, the condenser 192, the line conductor C139, the contacts 145 ofthe split key K140, the line conductor C165 and the contacts 151 of thelink key K150 to the line conductor C112 of the trunk linel 110.Finally, at the contacts 152 and 155 of the link key K150, a connectionis completed between the line conductors C385 and 038| in the cable 300and the repeater 6I0, this connection extending from the line conductorC385 in the cable 380, the contacts 152 of the link key K150, the lineconductor C163, the contacts 143 of the split key K140, the lineconductor C615, the contacts 65|, the windings 6H and 6I2 of therepeater 6I0, the line conductor C616, the condenser 192, the lineconductor C139, the contacts 146 of the split key K140, the lineconductor C166 and the contacts 155 of the link key K150 to the lineconductor C38I in the cable 380. Accordingly, at this time, theapparatus in the trunk circuit at the rst dispatcher position 600 isoperatively connected to both the repeater 305 in'the first link 300 inthe dispatcher exchange 30 and the subscriber substation T2 in the P. A.X 40, the telephone station TI in the dispatcher exchange 30 being'operatively connected to the repeater 305, as previously noted. Hence,a three-way communication connection including the telephoneA stationTl, the subscriber substation T2 and the rst dispatcher position 600 iscompleted at this time.

With the link key K150 thus operated, the dispatcher at the rstdispatcher position 600 may split the connection in either direction byselectively operating the split key K140i in the trunk circuit at hisposition. More particularly, in order to split the connection and talkto the person at the calling telephone station Tl in the dispatcherexchange 50 to the exclusion of the subscriber at the calledsubscriliverY substation T2, the dispatcher at the iii-st dispatcherposition G operates the split key K113i! to its front position. When thesplit key Kllil is operated to its front position the previously tracedconnection between the repeater 5i@ and the trunk line lll@ extending tothe PA.. X ill is interrupted ,at the contacts F52 and 'E55 thereof;and, at the contacts ll of the split key K'li, there is ccmpleted abridge path between the line conductors Gili and CH2 of the trunk linellt, thereby to retain the connector switch Mi in the l2. X liti in itsoperated. position. This bridge path extends trom the line conductorC'l'il o the trunk line il@ by way of the contacts *55 o the link keyK'lil, the line conductor (1165i, the resistor itil'. the contacts 'itof the split key Kidd, the line conductor 0F65 and the contacts l5? ofthe link key ll'l to the line conductor Cl'i of the trunk line lid. Onthe other hand, order to split the connection and talk to the subscriberat the. called subscriber substation. TZ in the P'. A. X til to theexclusion of the person at the calling telephone station Ti in thedispatcher exchange 35, the dispatcher at the iirst dispatcher position56@ operates the split key Kilt@ to its rear position. When the splitkey Kid@ is operated to its rear position the previously tracedconnection between the repeater @iii and the cable 35i@ extending to therepeater 355 in the first link 305 is interrupted at 'the contacts 153and 1&5 thereof; and, at the contacts 156i of the split key K150, thereis cornpleted a bridge path between the line conductors C176 and CH2 ofthe trunk line 'l, thereby to retain the connector switch B2i in itsoperated position. This bridge Apath extends from the line conductorC'lll of the trunk line 110 by way of the contacts 154 of the link keyK150, the line conductor C164, the resistor 190, the contacts 144 of thesplit key K148i, the line conductor C165 and the contacts 151 of thelink key K150 to the line conductor C112 of the trunk line 110.

After the dispatcher at the first dispatcher position 600 renders thedesired service to the person at the calling telephone station TI in thedispatcher exchange 30 or to the subscriber at the called subscribersubstation T2 in the P. A. X 40, he returns the link key K150 to itsnormal position, thereby to recomplete the previously traced directconnection between the telephone station Tl and the subscribersubstation T2 and to free the trunk circuit at the first dispatcherposition 600. More particularly, when the link key K150 is returned toits normal position there is interrupted, at the contacts 158, thepreviously mentioned holding circuit for energizing the winding of theswitching relay R650, thereby to cause the latter relay to restore. Atthis time, the apparatus at the rst dispatcher position 600 iscompletely released.

At any time, the dispatcher at the first dispatcher position 600 maydetermine the particular telephone station in the dispatcher exchange30, included in an established connection extending between thedispatcher exchange 30 and l the P. A. X 40 by way of one of the linksin the group of links individually associated with the rst dispatcherposition 600, by operating the corresponding link identity key in thetrunk circuit at the rst dispatcher position 600. For example, in orderto verify the telephone station included in the established connectionbetween the telephone station Tl in the dispatcher exchange 3;@ and thesubscriber substation T2 in the P. A. X it routed by Way of the firstlink 3d@ and the trunk line'llil, the dispatcher at the rst dispatcherposition '505 operates the link identity key Kllli in the trunk circuitat the first dispatcher position the link identity key K'liill beingindividual to the rst link 356. V/'hen the link identity key E216@ isthus operated there is completed, at the contacts 'it thereof, a circuitfor energizing the winding of the cutoi relay R52@ in the identitydistributor unit 5t@ individually corresponding to irst dispatcherposition this circuit extending from ground by way of the contacts 55S,5t@ and 539, the Winding of R520, Ci'l, the contacts liti of the linkidentity key Kit@ and the resistor 'E35 to battery. When thus energizedthe cutoi relay R522@ operates to interrupt, at the contacts and. 523, acircuit substantially identical to that previously traced for energizingthe windings of the cutoff relays R535, and respectively correspondingto the second, third and fourth dispatcher positions. Accordingly, theoperated cutoi relay R52@ individually corresponding to the firstdispatcher position @Citi prevents operation oi the cutoi relays R536;R563@ and R555 individually corresponding to the second, third andfourth dispatcher positions. Hence, it will be understood that, when theidentity distributor unit 555 is being utilized by the dispatcher at therst dispatcher position 5G51 to identify a telephone station in thedispatcher exchange 30, the identity distributor unit 555 is lockedagainst use by the dispatchers at the other dispatcher positions.

Also, upon operating, the cutoff relay R520 completes, at the contacts526i, an obvious cir-

